Search academic texts

Information × Registration Number 0211U002776, 0107U004321 , R & D reports Title Investigation of nuclear-physical parameters and elaboration of method and subcriticism and operatio means in critmass risk zones popup.stage_title Head Vysotskiy E. D., Registration Date 24-02-2011 Organization Institute for Safety Problems of Nuclear Power Plants popup.description2 The object of study - accumulation of fuel material, localized and hidden in the areas of penetration of the foundation slab of the reactor cavity in the southeastern quarter under-reactor room 305/2 Shelter. Results. We study the dynamics of a powerful neutron anomalies recorded in June 1990 show that the anomaly was caused by "cold, critical incident" in the southeast quarter of room 305/2. Acceleration and self-extinguishing incidents occurred during the water intake in fuel-containing materials, hidden in the area of penetration. Calculations of neutron and thermal characteristics of critical assemblies (fuel-moderator-reflector), the mass and geometric parameters, which correspond to the real conditions of existence of hidden clusters were performed. It was found that a critical mass of fuel-containing materials (up to 40 m) is located in the waterlogged condition for a second critical value. Permanent presence of water in the area of penetration is a factor that stabilizes the subcritical clusters. We propose a version of " blast-furnace " process of the formation of hidden clusters, in which the interaction of molten fuel with the concrete foundation slab and charge of the fragments of the core light oxide layer ("slag", uranium less than 5% by weight) forms the horizontal flow of black lava-like fuel-containing materials, and heavy lower layer (uranium more than 50% by weight) remains in the area of penetration and provides a critical mass of fuel. Scope. The results of the work will be used in developing measures to ensure nuclear safety of the Shelter. Conclusions. Rising temperatures and dehydration hidden accumulations of fuel mass as a result of construction of a new safe confinement can lead to recurrent criticality and self-sustaining chain reaction with consequences related severe nuclear incident. Product Description popup.authors Іванов В. Довидьков А. Михайлов О. Передерій А. Шостак В. popup.nrat_date 2020-04-02 Close